Knowing the Risks of Erionite and Crystalline Silica

Erionite is a naturally occurring mineral found in fine-grained sediments such as volcanic ash deposits that have been altered by weathering and ground water. Erionite exists as a form of asbestos — one that some reports show to be more carcinogenic than the regulated asbestos forms — and has not been regulated since there are no commercial uses for it. UOSH has issued a recent publication from the CDC and NIOSH. We recommend that you review that document, but have summarized key information and recommendations below.

Erionite made its presence known on the world stage due to an array of unexplained mesothelioma deaths and illnesses in Tuzkoy, Turkey, which happened to be sitting on top of an erionite deposit. It has been found in all western US states, with the exception of Washington, and has been found further north in British Columbia. Small deposits of erionite have been found in Utah, north of Duchesne, and on the south slopes of the Uinta Mountains. Other deposits that have not been documented may also exist. As is common with rock, erionite may be eroded down the drainage of the exposed rock areas.

Crystalline silica is another mineral commonly found in many geologic formations, typically as quartz. Occupational exposure to respirable crystalline silica has been associated with silicosis, lung cancer, and other airway diseases. OSHA’s silica rule for construction (29 CFR 1926.1153 Respriable Crystalline Silica) which is in force in all federal OSHA states will also be in force in Utah. The Utah legislature passed it in the 2018 session, and it will now be posted by the Labor Commission for a 90 day comment period. The UOSH Compliance group will start enforcing it on October 1, 2018. The rule is applicable to all public and private employers in Utah, and it applies to any construction activity. Maintenance of existing roadways, modification (remodel) of structures including concrete cutting or grinding, re-pointing brick and other activities fall under the construction category.

One activity often done by public entities or hired contractors of those entities is leveling sidewalks by grinding off high spots. This function also falls under this standard. Past air sampling for this specific activity has found operators considerably over the PEL of the old standard. If the operator is not using engineering methods, such as a shroud and vacuum system, to minimize the amount of dust that is allowed to escape, they are exceeding the new PEL. Besides the threat to the health of employees, allowing this dust to escape into community air is hazardous for residents — especially children — in those communities. The unusual feature of this standard, as opposed to other OSHA chemical standards, is that the employer does not need to do an assessment of the hazard, if they are doing the activity in compliance with the methods outlined in Table 1 of the standard (Specified Exposure Control Methods). If the work is being done as described for that activity in the table, it is assumed that the exposure to employee(s) is below the PEL and no air sampling assessment must be completed. This is the first time OSHA has used this idea and it prevents employers from being required to do sometimes time-consuming and costly personal sampling.

Erionite fibers and crystalline silica only pose health hazards when they are disturbed and become airborne, which may occur during road maintenance and construction. Specialized heavy equipment, including that used in blading and grading, produce dust when maintaining and smoothing roads, while culverts, roadside drainage ditches, and cattle guards require periodic cleaning that may produce dust hazards. For example, road blading/grading observations conducted by the Health Hazard Evaluation Program indicated that while the driver and any occupants in a truck used for construction or maintenance would be protected from dust by the cab, it created a large dust cloud as it traveled down the road that would expose anyone downwind of the vehicle.

For employee health and safety, minimizing dust exposure during dust-generating activities is essential. Below are a number of recommendations that can be implemented in order to protect against not only erionite, but other airborne hazards:

Avoid using aggregate that is known or suspected to contain erionite to repair roads.

Keep the windows and doors to the equipment operator’s cabs closed when operating equipment or driving down dirt roads.

Maintain equipment air filters regularly as recommended by the equipment manufacturers. Change gaskets and seals when signs of age (i.e., cracking or wear) or damage occur. Air intake filters should have a MERV of 16 and should be a powered, pressurized system. The recommended flow rate should be between 40 and 140 cubic feet per minute. The filtration efficiency of the recirculation filter should be between a MERV-14 and MERV-16 filter at a flow rate of 200 – 300 cubic feet per minute.

Develop a maintenance schedule and standard operating procedure to maintain the local exhaust ventilation system in the minerals lab.

Conduct full-shift personal air sampling for respirable crystalline silica. If immediate efforts to reduce dust levels are not successful in reducing silica levels below the most protective occupational exposure limit, implement a respiratory protection program that meets the requirements of the OSHA respiratory protection standard. Ensure employees are medically cleared, fit-tested, clean-shaven, and adequately trained on respirator use and care before using respirators. Re-sample after additional controls have been put in place to confirm that exposures are consistently below applicable occupational exposure limits before eliminating respirator use.

Inform employees of the need to use dust control methods during any work and train them on dust control techniques.

Wet the soil or aggregate before disturbing it to reduce dust generation. It is common practice at construction and other outdoor work sites to use water trucks for dust suppression.

Restrict dust-generating activities to conditions conducive to reducing dust generation. Avoid dust-generating tasks on windy days. When possible, schedule dust-generating tasks on days when the soil is moist.

Educate employees on the health effects and hazards of crystalline silica and erionite, how they may be exposed, and control measures.

Train employees in proper work practices for working with soil or aggregate that may contain crystalline silica or erionite.

Personal protective equipment is the least effective means for controlling hazardous exposures. It requires a comprehensive program and high level of employee involvement and commitment. The right personal protective equipment must be chosen for each hazard. Training, change-out schedules, and medical assessment may be needed. Personal protective equipment should not be the sole method for controlling hazardous exposures, but should be used until effective engineering and administrative controls are in place.